NSASM is the assembler for National Semiconductor's COP8 microcontrollers.
NSASM March 21 2003 release 5.5, tools version 5.5.0
Here is a Beta version of the Linux distribution:
NSASM Linux BETA
Let me know if you try it out.
See the revision log to find out what has changed.
Here is the User Manual.
For NiceMon (Nation COP8Flash Debug Monitor) information, see the main page.